Public Release: 

Duke Studies Find Little Difference In Outcomes Between Bypass Surgery And Angioplasty For Diabetics

Duke University

NEW ORLEANS -- In contrast to the findings of a recent, highly publicized clinical trial and subsequent federal recommendation, two Duke University Medical Center studies suggest that diabetics with severe coronary artery disease do equally well if they receive either angioplasty or coronary artery bypass surgery.

While diabetics with multi-vessel disease tend to have slightly worse outcomes with both treatments when compared with non-diabetics with similar disease, the Duke researchers recommend that cardiologists not use diabetes as the main factor when considering which procedure is best for their patients.

The Duke studies were prepared for presentation Tuesday (Nov. 12) at the annual scientific meeting of the American Heart Association.

In July, investigators for a multi-center trial called BARI for Bypass Angioplasty Revascularization Investigation reported in the New England Journal of Medicine that the five-year survival for diabetics treated with bypass surgery was 80.6 percent, compared to 65.5 percent for diabetics treated with angioplasty. Shortly before the overall BARI results were published, the National Heart Lung Blood Institute recommended that diabetics with multi-vessel disease be treated with bypass surgery.

After the BARI results were published, Duke researchers conducted their own retrospective studies to see if the BARI results could be substantiated. While they acknowledge that their studies are retrospective, the researchers say the Duke studies provide more data that can be used in further discussion of the issue.

The studies were supported by, and drew upon the expertise of, the Duke Clinical Research Institute, which has been collecting and analyzing patient data relating to heart disease since 1969.

"Our long-term data show that a history of diabetes holds a similar risk for both angioplasty and bypass patients," said Dr. Greg Barsness, Duke cardiology fellow. "Rather than using diabetes to determine the revascularization choice, other factors should be considered, such as disease severity and technical considerations."

Barsness's study followed 3,220 patients (769 of whom were diabetic) who received either bypass or angioplasty at Duke between 1984 and 1990. After five years (the same follow-up for the BARI trial), 74.3 percent of the diabetics (vs. 86.3 percent for non-diabetics) who received bypass were alive, while 76.4 percent of diabetics (vs. 88.3 percent of non-diabetics) receiving angioplasty were alive.

"After adjusting for such factors as age, gender and characteristics of their heart disease, we found that diabetics receiving either angioplasty or bypass had lower survival than non-diabetics receiving these interventions," Barsness said. "However, in contrast to the results seen in the BARI trial, the decrease in survival was similar among both angioplasty- and bypass-treated diabetics."

For the second study, Dr. David Anderson, Duke cardiology fellow, pooled data from seven recent multi-center trials involving 6,338 patients who underwent angioplasty, 1,230 of whom were diabetics. Patients were followed for nine months after their procedures.

"At least for the short term, our study suggests that factors other than diabetes are more predictive of major adverse events after angioplasty," Anderson said. "Statistical analysis showed that while diabetics had slightly more revascularization during a nine-month follow-up period due to higher restenosis (where the artery closes again), other outcomes (death and heart attack) are best predicted by the number of diseased vessels feeding the heart, prior history of heart attack, and the degree of vessel blockage before the procedure."

Physicians still do not understand why diabetics tend to do worse than non-diabetics. While researchers have demonstrated that "tight" control of a diabetic's glucose levels significantly delays the disease's destructive effects on tiny blood vessels -- such as those in the eyes, extremities and kidneys -- they still do not know how the disease effects the body's larger blood vessels, like those supplying oxygen-rich blood to the heart.

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